Heart Rate Pro

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Generallya lower heart rate at rest implies more efficient heart function and better cardiovascular fitness. For example, a well-trained athlete might have a normal resting heart rate closer to 40 beats per minute.

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Put the tips of your index and middle fingers on your skin. Press lightly until you feel the blood pulsing beneath your fingers. You may need to move your fingers around until you feel it. Count the beats you feel for 10 seconds. Multiply this number by six to get your heartbeats per minute.

You may not feel symptoms of tachycardia. But it can mean there's a heart issue you need to be aware of. Certain heart conditions that cause tachycardia can lead to stroke, heart failure, or even sudden death. Your doctor will prescribe the best treatment for the cause of your tachycardia.

Bradycardia is a slow heart rate -- fewer than 60 bpm. Your resting heart rate typically drops below 60 bpm when you're sleeping. Some athletes and young adults can have heart rates of 40-60 bpm as well. More seriously, bradycardia results from your heart being unable to pump well enough to send oxygenated blood throughout your body. Bradycardia can make you dizzy, tired, weak, or short of breath, or you may feel no symptoms at all. Severe cases of bradycardia may require a pacemaker.

For most healthy adults, a normal resting heart rate is between 60 and 100 beats per minute. Children tend to have faster heart rates, while those of athletes might be lower. You can check your pulse most easily at your wrist or on the side of your neck. If you need to raise or lower your heart rate, talk with your health care provider about lifestyle changes and exercise programs that may be right for you.

Trained athletes can have very low heart rates, and children typically have higher ones. If you are neither and have a heart rate that stays below 60 bpm or above 100 bpm along with worrisome symptoms, you should see a doctor.

What should your heart rate be when working out, and how can you keep track of it? Our simple chart will help keep you in the target training zone, whether you want to lose weight or just maximize your workout. Find out what normal resting and maximum heart rates are for your age and how exercise intensity and other factors affect heart rate.

Important Note: Some drugs and medications affect heart rate, meaning you may have a lower maximum heart rate and target zone. If you have a heart condition or take medication, ask your healthcare provider what your heart rate should be.

Tell your health care professional if you have noticed that your heart rate has been beating slower or faster than usual. You may also have had symptoms such as feeling weak, dizzy or like you might faint.

Call 911 if your heart rate is suddenly very high or very low for you, especially if you have symptoms that may include chest pain, shortness of breath, dizziness, fainting or other signs that something is not right.

Heart rate is the frequency of the heartbeat measured by the number of contractions of the heart per minute (beats per minute, or bpm). The heart rate varies according to the body's physical needs, including the need to absorb oxygen and excrete carbon dioxide. It is also modulated by numerous factors, including (but not limited to) genetics, physical fitness, stress or psychological status, diet, drugs, hormonal status, environment, and disease/illness, as well as the interaction between these factors.[1] It is usually equal or close to the pulse rate measured at any peripheral point.[2]

While heart rhythm is regulated entirely by the sinoatrial node under normal conditions, heart rate is regulated by sympathetic and parasympathetic input to the sinoatrial node. The accelerans nerve provides sympathetic input to the heart by releasing norepinephrine onto the cells of the sinoatrial node (SA node), and the vagus nerve provides parasympathetic input to the heart by releasing acetylcholine onto sinoatrial node cells. Therefore, stimulation of the accelerans nerve increases heart rate, while stimulation of the vagus nerve decreases it.[6]

As water and blood are incompressible fluids, one of the physiological ways to deliver more blood to an organ is to increase heart rate.[5] Normal resting heart rates range from 60 to 100 bpm.[7][8][9][10] Bradycardia is defined as a resting heart rate below 60 bpm. However, heart rates from 50 to 60 bpm are common among healthy people and do not necessarily require special attention.[3] Tachycardia is defined as a resting heart rate above 100 bpm, though persistent rest rates between 80 and 100 bpm, mainly if they are present during sleep, may be signs of hyperthyroidism or anemia (see below).[5]

There are many ways in which the heart rate speeds up or slows down. Most involve stimulant-like endorphins and hormones being released in the brain, some of which are those that are 'forced'/'enticed' out by the ingestion and processing of drugs such as cocaine or atropine.[11][12][13]

The heart rate is rhythmically generated by the sinoatrial node. It is also influenced by central factors through sympathetic and parasympathetic nerves.[15] Nervous influence over the heart rate is centralized within the two paired cardiovascular centres of the medulla oblongata. The cardioaccelerator regions stimulate activity via sympathetic stimulation of the cardioaccelerator nerves, and the cardioinhibitory centers decrease heart activity via parasympathetic stimulation as one component of the vagus nerve. During rest, both centers provide slight stimulation to the heart, contributing to autonomic tone. This is a similar concept to tone in skeletal muscles. Normally, vagal stimulation predominates as, left unregulated, the SA node would initiate a sinus rhythm of approximately 100 bpm.[16]

Parasympathetic stimulation originates from the cardioinhibitory region of the brain[17] with impulses traveling via the vagus nerve (cranial nerve X). The vagus nerve sends branches to both the SA and AV nodes, and to portions of both the atria and ventricles. Parasympathetic stimulation releases the neurotransmitter acetylcholine (ACh) at the neuromuscular junction. ACh slows HR by opening chemical- or ligand-gated potassium ion channels to slow the rate of spontaneous depolarization, which extends repolarization and increases the time before the next spontaneous depolarization occurs. Without any nervous stimulation, the SA node would establish a sinus rhythm of approximately 100 bpm. Since resting rates are considerably less than this, it becomes evident that parasympathetic stimulation normally slows HR. This is similar to an individual driving a car with one foot on the brake pedal. To speed up, one need merely remove one's foot from the brake and let the engine increase speed. In the case of the heart, decreasing parasympathetic stimulation decreases the release of ACh, which allows HR to increase up to approximately 100 bpm. Any increases beyond this rate would require sympathetic stimulation.[16]

The cardiovascular centre receive input from a series of visceral receptors with impulses traveling through visceral sensory fibers within the vagus and sympathetic nerves via the cardiac plexus. Among these receptors are various proprioreceptors, baroreceptors, and chemoreceptors, plus stimuli from the limbic system which normally enable the precise regulation of heart function, via cardiac reflexes. Increased physical activity results in increased rates of firing by various proprioreceptors located in muscles, joint capsules, and tendons. The cardiovascular centres monitor these increased rates of firing, suppressing parasympathetic stimulation or increasing sympathetic stimulation as needed in order to increase blood flow.[16]

Similarly, baroreceptors are stretch receptors located in the aortic sinus, carotid bodies, the venae cavae, and other locations, including pulmonary vessels and the right side of the heart itself. Rates of firing from the baroreceptors represent blood pressure, level of physical activity, and the relative distribution of blood. The cardiac centers monitor baroreceptor firing to maintain cardiac homeostasis, a mechanism called the baroreceptor reflex. With increased pressure and stretch, the rate of baroreceptor firing increases, and the cardiac centers decrease sympathetic stimulation and increase parasympathetic stimulation. As pressure and stretch decrease, the rate of baroreceptor firing decreases, and the cardiac centers increase sympathetic stimulation and decrease parasympathetic stimulation.[16]

There is a similar reflex, called the atrial reflex or Bainbridge reflex, associated with varying rates of blood flow to the atria. Increased venous return stretches the walls of the atria where specialized baroreceptors are located. However, as the atrial baroreceptors increase their rate of firing and as they stretch due to the increased blood pressure, the cardiac center responds by increasing sympathetic stimulation and inhibiting parasympathetic stimulation to increase HR. The opposite is also true.[16]

Increased metabolic byproducts associated with increased activity, such as carbon dioxide, hydrogen ions, and lactic acid, plus falling oxygen levels, are detected by a suite of chemoreceptors innervated by the glossopharyngeal and vagus nerves. These chemoreceptors provide feedback to the cardiovascular centers about the need for increased or decreased blood flow, based on the relative levels of these substances.[16]

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